In some cases, an ailment may affect the quality of a patient's sleep and/or affect the patient's activity level. For example, chronic pain may cause a patient to have difficulty falling asleep, disturb the patient's sleep, e.g., cause the patient to wake, and prevent the patient from achieving deeper sleep states, such as one or more of the nonrapid eye movement (NREM) sleep states. Chronic pain may also cause a patient to avoid particular activities, or activity in general, where such activities increase the pain experienced by the patient.
Other ailments that may negatively affect patient sleep quality and patient activity level include movement disorders, such as tremor, Parkinson's disease, multiple sclerosis, epilepsy, or spasticity. Such movement disorders may result in irregular movement or activity, as well as a generally decreased level of activity. Further, the uncontrolled movements associated with such movement disorders may cause a patient to have difficulty falling asleep, disturb the patient's sleep, or cause the patient to have difficulty achieving deeper sleep states.
Psychological disorders, such as depression, mania, bipolar disorder, or obsessive-compulsive disorder, and other disorders including sleep apnea, congestive heart failure, gastrointestinal disorders and incontinence, may also similar affect the ability of a patient to sleep, or at least experience quality sleep. In the case of depression, a patient may “sleep” for long periods of the day, but the sleep is not restful, e.g., includes excessive disturbances and does not include deeper, more restful sleep states. Further, during the day, psychological disorders may also affect the general activity level of a patient. For example, patients with depression may spend a significant majority of their time in bed or otherwise prone. Movement disorders and psychological disorders are examples of neurological disorders.
Congestive heart failure is another example of a disorder that affects both sleep quality and activity. Patients with congestive heart failure may lack the stamina for activity during the day, and may have difficulty breathing at night, which may affect the quality of their sleep. In some cases, the above-identified ailments may be treated via an implantable medical device (IMD), such as an implantable stimulator or drug delivery device.
Further, in some cases, poor sleep quality may increase the symptoms experienced by a patient due to an ailment. For example, poor sleep quality has been linked to increased pain, movement disorder and psychological disorder symptoms in chronic pain patients. The link between poor sleep quality and increased symptoms is not limited to ailments that negatively impact sleep quality, such as those listed above. Nonetheless, the condition of a patient with such an ailment may progressively worsen when symptoms disturb sleep quality, which in turn increases the frequency and/or intensity of symptoms. The increased symptoms may, in turn, limit patient activity during the day, and further disturb sleep quality.